Lyle Petersen, director of CDC’s Division of Vector-Borne Infectious Diseases, reiterated previous warnings that this year may yield the highest number of cases ever since the disease was first found in the United States in 1999.

“We think the numbers may come close to or even exceed the total number of cases reported in 2002 and 2003,” both of which were severe West Nile virus years, Petersen said during a conference call. More than 260 deaths were reported in those years.

Health officials expected the West Nile virus, which humans contracted through mosquito bites, to continue to peak into September and early October, when the disease typically reaches its peak.

Over 70% of the cases have been reported in six states, with Texas being the most infected at 45% followed by South Dakota, Mississippi, Oklahoma, Louisiana, and Michigan.